A technique that involves the use of electrical coils on the head to generate a brief magnetic field which reaches the cerebral cortex. It is coupled with electromyography response detection to assess cortical excitability by the threshold required to induce MOTOR evoked potentials. This method is also used for brain mapping, to study neurophysiology, and as a substitute for electroconvulsive therapy for treating depression. Induction of seizures limits its clinical usage.